When Do Not Track is enabled in a browser, it signals to Websites and to advertisers that the user around the Web for ad targeting purposes. Ad networks and sites aren't required to comply, but , and the U.S. government is now pressuring more companies to play along, .

Hence Do Not Track in Google Chrome. Google spokesman Rob Shilkin specifically called out the company's pact with the White House as its reason for adding the feature in the Chromium developer channel in a Do Not Track should be available in the stable version of Chrome by the end of the year, he said.

Google will be the last of the major browser makers to add a Do Not Track option, which is already available in Firefox, Internet Explorer and Safari. Third-party are available as well.

Broad participation may seem like good news, but Do Not Track is still controversial. Because the setting doesn't guarantee privacy across all Websites, it could give users a and the seediest advertisers .

Do Not Track also treads on thin ice among advertisers who do participate. They're hoping that even if the tool is widely available, most people won't bother to enable it. Microsoft's recent decision to make Do Not Track in Windows 8 jeopardizes that idea. The developers of Apache Web server have already said they'll as a result.